Parallel prosessing of microfluidic devices

ABSTRACT

Microfluidic arrangement which comprises A) a number of microfluidic devices, and B) an instrument which comprises a spinner motor and a rotary member arranged such that liquid flow can be driven centrifugal force in each of the devices by spinning the. Each of the microfluidic devices comprises microchannel structures in a common planar layer I. The characteristic feature is that layer I of each device can be oriented radially and at an angle ≠0° relative to the plane of the rotary member, with preference for 90°. The rotary member has seats for holding the devices. A microfluidic device comprising i) two essentially planar and parallel opposite sides, and edge sides, ii) a set of one, two, three or more essentially equal microchannel structures, each of which comprises a first inlet arrangement comprising an inlet port IP I 1 . The characteristic feature is that a) each of the inlet ports is present in an edge side, and b) the wettability of the inner walls of said first inlet arrangement permits penetration by capillarity of at least a predetermined first volume of an aqueous liquid.

TECHNICAL FIELD

The present invention relates to the miniaturization of analytical,synthetic, preparative etc procedures within chemical and biologicalsciences.

One aspect of the invention is a microfluidic instrument arrangement,which comprises a) one, two or more essentially equal microfluidicdevices, and b) an instrument for processing the microfluidic devices.Additional aspects are: i) the instrument as such, ii) the use of theinstrument for processing the microfluidic device (method ofprocessing), iii) a microfluidic device as such, and (iv) a method forloading a predetermined liquid aliquot to each of the microchannelstructure of a microfluidic device (“Dip-Chip technology”). Theinstrument may be used for processing different kinds of microfluidicdevices. The microfluidic device may be processed in the innovativeinstrument but also by the use of other instruments and/or other means.The microfluidic device of item (iii) is adapted to the Dip-Chiptechnology.

A microfluidic device comprises a number of microchannel structuresthrough which a liquid flow is used for transporting analytes, reactantsetc. Devices used in the innovative arrangement/instrument utilizecentrifugal force created by spinning the devices for the transportwithin at least a part of each microchannel structure. Devices of aspect(iii) above do not need to utilize centrifugal force for driving liquidflow.

BACKGROUND TECHNOLOGY

Patents and patent applications cited in this specification are herebyincorporated by reference in their entirety.

Microfluidic Systems

The use of centrifugal force for moving liquids within microfluidicsystems on circular platforms has been described among others by AbaxisInc (U.S. Pat. No. 5,122,284, U.S. Pat. No. 5,591,643, U.S. Pat. No.5,160,702, U.S. Pat. No. 5,472,603, WO 9533986, WO 9506870); MolecularDevices (U.S. Pat. No. 5,160,702); Gamera Biosciences/Tecan (WO 9721090,WO 9807019, WO 9853311), WO 01877486, WO 0187487; Gyros AB/AmershamPharmacia Biotech (WO 9955827, WO 9958245, WO 0025921, WO 0040750, WO0056808, WO 0062042, WO 0102737, WO 0146465, WO 0147637, WO 0147638, WO0154810, WO 0241997, WO 0241998, WO 0275312, WO 274438, WO 0275775, WO0275776, WO 03018198, WO 03024598 and WO 03093802 (SE0201310-0).

Centrifugal force has also been used for sector-shaped microfluidicdiscs. See WO 9607919 (Biometric Imaging).

WO 0173396 (Caliper) describes a microfluidic device in which there areinlet ports designed as capillary tips.

Non-Microfluidic Systems

Chromatographic columns have been placed in centrifugal rotors andspinning used for driving samples and other liquids through the columns.

Sedimentation in packed columns that are oriented parallel to each otherin the same radial direction in a centrifugal field has been utilizedfor performing blood tests. See for instance U.S. Pat. No. 6,114,179 andU.S. Pat. No. 5,338,689 (Stiftung für diagnostische Forschung).

Other non-microfluidic systems based on circular discs that can be spunhave been described in U.S. Pat. No. 4,469,973 (Guigan), U.S. Pat. No.4,519,981 (Guigan), U.S. Pat. No. 4,390,499 (IBM), EP 392475 (Idemitsu)and many others.

Problems Associated with Prior Microfluidic Techniques UtilizingCentrifugal Force.

Procedures within chemical and biological sciences have been adapted tominiaturized formats in order to increase the productivity of performinganalytical, synthetic, preparative etc. There is a general desire toincrease a) the total number of successful tests per time unit, per testdevice and per instrument, and b) the number of successful tests/resultsfrom a given volume/amount of sample, reagent, etc.

Miniaturization often creates new problems and/or accentuates problemsthat are easy to handle in larger systems. Interfacing to a microfluidicdevice is more difficult the smaller and/or more dense-packed themicrochannel structures are. The risk for inaccuracies in the transferof liquid from the instrument to the individual microchannel structuresincreases dramatically when going down in the μl-range, in particularwhen entering into its lower part (sub-μl-range or nanolitre range,nl-range including picolitre range). The significance of losses causedby undesired evaporation and by irregular adherence to surfacesincreases dramatically. Intermolecular forces become more important thatmay lead to a liquid behaviour that is different compared to largerscales. In total technical solutions that are applicable to themacroworld many times are not always applicable to the microworld. Newtechnical solutions and modifications are required.

OBJECTS OF THE INVENTION

Objects of the invention are to provide an instrument for processing ofidentical or different microfluidic devices, which enables:

-   -   a) parallel processing of larger numbers of microchannel        structures and/or microfluidic devices; and/or    -   b) enhanced versatility for the user with respect to the number        and the type of microfluidic devices that can be processed in        parallel; and/or    -   c) parallel storage of similar and/or dissimilar liquid volumes        in individual microchannel structures before their use in an        intended procedure; and/or    -   d) driving a liquid flow in various directions relative to a        predetermined main direction of a microchannel        structure/microfluidic device, e.g. i) back and forth in a        predetermined part of a microchannel structure, ii) in the main        direction in one part of a structure and in some other        direction, for instance opposite direction, in another part etc;        and/or    -   e) larger numbers of process steps and process microcavities per        microchannel structure; and/or    -   f) individual examination and/or irradiation of the devices        without imperative removal of devices from the instrument;        and/or    -   g) individual regulation of liquid flow velocity in the devices;        etc.

Item d. ii) typically means that the liquid flow is in the maindirection in the upstream part of a microchannel structure and in theopposite direction in a subsequent downstream part, typically the lastpart of the structure. The definition of “main direction” is given underthe heading “Microfluidic device”.

Item f) includes that the liquid flow velocity in corresponding parts ofthe microchannel structures in one device may differ in a predeterminedmanner from the liquid flow velocity in corresponding parts of anotherdevice that is processed in parallel.

Another object is a microfluidic device that has an inlet arrangement,which simplifies a rapid, reproducible, reliable and accurate loading ofwell-defined minute liquid volumes to the individual microchannelstructures of the device. This object in particular emphasizes volumesin the nl-range, i.e. ≦5,000 nl.

Terms, such as larger, enhanced, simplify etc, are relative to knowntechnology.

Where appropriate these objects apply also to methods utilizing theinnovative instrument, the innovative microfluidic device and/or theinnovative arrangement.

These objects concern microfluidic systems in which electrokineticand/or non-electro kinetic liquid flow is utilized. Centrifugal force orother inertia forces, or pressure differences created externally orinternally within the individual microchannel structures may be used forcreating non-electrokinetic liquid flow. Applying overpressure at theinlet and/or sub-pressure at the outlet of a microconduit/microchannelstructure (relative to atmospheric pressure) may create useful pressuredifferences.

A liquid flow may be active or passive. In principle a liquid flow thatis not driven solely by capillarity is active and typically created byexternal means. Active liquid flow includes flow driven by centrifugalforce and other inertia forces, and any other force mentioned herein(except capillary force). Passive liquid flow and capillary liquid floware in principle synonymous.

DRAWINGS

The first digit in each reference number refers to the figure while thesubsequent two digits refer to the detail concerned.

FIGS. 1 a-d illustrate views of a variant of the innovative microfluidicarrangement which contains an annular arrangement of 10 microfluidicdevices. FIG. 1 a is a side view of the arrangement. FIG. 1 b is a viewfrom above. FIG. 1 c is a slanted view from above. FIG. 1 d is a viewthrough the cross-section defined by plane A-A and illustrates thatdevices can be oriented radially.

FIGS. 2 a-d illustrate views of a variant which contains an annulararrangement of 4 microfluidic devices. The arrangement is viewed in thesame directions as in FIG. 1. FIG. 2 d illustrates that the devices canbe rotated, i.e. can have different orientations relative to the radiuspassing from the centre of the annular arrangement through the device.

FIG. 3 a-d illustrates schematically a rectangular form of theinnovative microfluidic device, which is constructed from several planarsubstrates and comprises five microchannel structures. FIGS. 3 a-c areslanted views on a bottom substrate layer, an intermediate substratelayer, and a top substrate layer, respectively. FIG. 3 d illustrates howthese substrate layers are joined together to form the microfluidicdevice with its microchannel structures.

THE INVENTION

Microfluidic Instrument Arrangement (First Aspect)

This aspect is illustrated in FIGS. 1 and 2. It comprises two mainparts:

-   -   A) One or more essentially equal microfluidic devices (101 a,b .        . . , 201 a,b . . . ), for instance of the kind (300) shown in        FIG. 3. Each of the devices comprises a set (set I) of one or        more essentially equal microchannel structures (304 a,b . . . ,        FIG. 3) that are comprised within a common generally planar        layer of the device (layer I). Each of the microchannel        structures comprises an internal microconduit portion (308 a,b .        . . , FIG. 3) in which an active liquid flow is used for        transport of liquid, reactants and the like in the downstream        direction. Further details about layer I and the internal micro        conduit portions (308) are given under the heading “Microfluidic        device”.    -   B) An instrument (100,200), which comprises a spinner motor        (102,202) and a rotary member (103,203). The instrument is        intended for processing the microfluidic devices (101 a,b . . .        , 201 a,b . . . ).

As illustrated in FIGS. 3 a-c, the microchannel structures typically arecomposed of microstructures deriving from different substrate layers incase the device is constructed from two or more planar substrates thatare joined together. For the variant shown in FIG. 3, layer I comprisesat least the upper part of planar substrate I, whole planar substrateII, and the lower part of substrate III.

The rotary member (103,203) typically has an axis of symmetry (C_(n)with n≧2, 3, 4 etc up to ∞) that coincides with a spin axis (104,204). nare in preferred variants ≧5 including in particular circular variants(n=∞). The rotary member (103,203) is spun around the spin axis in aspin plane that is perpendicular to the spin axis.

The first aspect comprises two main characteristic features incombination.

The first main characteristic feature is that the rotary member(103,203) comprises a group (group A) of one or more seats (105 a,b . .. , 205 a,b . . . ) for retaining at least one of the microfluidicdevices (101 a,b . . . , 201 a,b . . . ) on the rotary member. Each ofthe seats can i) be positioned at the same radial distance as any of theother seat of the group, and ii) align layer I essentially radially atan angle a relative to the spin plane where 0°<α≦90°, with preferencefor 45°≦α≦90°, such as α being essentially equal to 90° (as illustratedin FIGS. 1-2).

Essentially equal to 90° includes α that is in the interval 85°-90°.

For variants where layer I has an essentially radial orientation and αis essentially equal to 90°, an extension of the device inwards the spinaxis (104,204) will typically intersect this axis or, when αis 90°,fully encompass it. In preferred variants this applies also to layer I.FIGS. 1-2 illustrate a variant where α is equal to 90°.

The arrangement may also comprise other kinds of microfluidic devices(not shown). In this case the rotary member may comprise separate groupsof seats (group B, group C etc) for one or more of these other kinds ofdevices. Devices of different kinds may or may not fit into a specificgroup of seats.

In preferred variants, the microchannel structures of set I areessentially parallel. Each of the seats (105 a,b . . . , 205 a,b . . . )of a group, in particular group A, can position corresponding parts ofthe internal microconduit portions (308 a,b . . . , FIG. 3) ofmicrochannel structures (304 a,b . . . , FIG. 3) of set I in differentmicrofluidic devices at essentially the same radial distance from thespin axis (104,204). This also applies for other sets (II, III etc) ofmicrochannel structures, if present.

The second main characteristic feature is that the microconduit portion(308 a,b . . . , FIG. 3) of each of the microchannel structures (304 a,b. . . , FIG. 3) in each of the microfluidic devices (101 a,b . . . , 201a,b . . . ) has an upstream part and a downstream part and aninterconnecting part that permits liquid transport/flow from theupstream to the downstream part when the device (101 a,b . . . , 201 a,b. . . ) is placed in the rotary member (103,203) and spun around thespin axis (104,204). Typically, the upstream part is then at a shorterradial distance from the spin axis than the downstream part during.

The Instrument

The innovative instrument (100,200) illustrated in FIGS. 1-2 comprises aspinner motor (102,202) and a rotary member (103,203). The spinner motorcomprises a shaft (106,206) with a spindle (107,207) through which theaxis of symmetry/spin axis (104,204) passes, and is mounted on a frame(108,208). The rotary member (103,203) has on its upper side one or moreseats (105 a,b . . . , 205 a,b . . . ) for holding a certain number ofmicrofluidic devices (101 a,b . . . , 201 a,b . . . ) (ten and four inFIGS. 1 and 2, respectively). Each seat may hold one, two or moremicrofluidic devices.

Each microfluidic device shown in these figures has inlet ports in theform of protrusions (109,209). Each protrusion comprises an internalmicroconduit of capillary dimension and may be in the form of a tipseparately attached to the surface of the microfluidic device. Theprotrusions in FIGS. 1-2 are attached to an edge side (=first edge side,303 a in FIG. 3 d) of a microfluidic device that is disc-shaped.

The total number (x) of seats (105 a,b . . . , 205 a,b . . . ) that ispossible on the rotary member (103,203) depends on the size of therotary member, the size of the seats, the size of the microfluidicdevices that are to be placed in the seats (thickness, extension in theradial direction etc), radial position of the seats, number of annularcircles of seats/microfluidic devices, ability of the seats/devices tobe rotated etc. Typical x may be found in the interval 2≦x≦1000, such as2≦x≦100. This interval applies to many microfluidic devices that have alength to be oriented radially that is within the interval 2-30 cm.

Each seat (105,205) preferably is designed to secure that a microfluidicdevice placed in the seat can be retained while spinning the rotarymember (103,203). This retaining function may, for instance, be ageometric configuration in the surface of the rotary member matching thepart of a microfluidic device that is to be placed in the seat.Geometric configurations may be in the form of one or more groovesand/or one or more pins and/or other elevated and/or recessedstructures. Sub-pressure and/or magnetic forces may also be used,typically in combination with geometric configurations and otherretaining functions. There may be further functionalities for retainingthe devices on the rotary member, for instance a top plate (110,210)that can be pressed to the upper parts of devices (101,201) that areplaced in the seats (105,205) of the rotary member (103,203). This topplate (110,210) may comprise retaining functions on the side that isturned against the rotary member (typically the lower side of the topplate).

Retaining functions that are based on sub-pressure require introductionof sub-pressure on the rotary member (103,203). This is typically donefrom a non-rotary part of the innovative instrument, possibly involvingalso rotary parts other than the rotary member (103,203). Examples ofother rotary parts are the spindle (106,206) and/or the shaft (107,207).The sub-pressure connection between a rotary part and a non-rotary partpreferably a) provides low or no friction between these parts whenspinning the rotary member and/or b) permits leakage of air between therotary part and the non-rotary part concerned. A preferred variant isillustrated in WO 03024596 (Gyros AB). Also other kinds of connectionsmay be used.

Retaining functions that are based on magnetic forces requires thateither one or both of the microfluidic device (101 a,b . . . , 201 a,b .. . ) or the rotary member (103,203) with its seats (105,205) comprisemagnetic or magnetizable material.

One or more of the seats may be designed to permit rotation of amicrofluidic device (201) about an axis that is parallel to but remotefrom the spin axis (204) of the rotary member (203). This axis typicallyis unique for each seat and passes through the seat and/or a deviceplaced in the seat. The rotation may be a full turn or a part of a turn.The rotation of the devices is in a plane that is parallel to the planeof the rotary member (spin plane). In a subvariant, one or more,preferably all, of the seats of a group may have two or more alternativeretaining structures (e.g. geometric) that enables orientation of amicrofluidic device at fixed angles relative to the radius passing fromthe centre of the rotary member through the seat concerned. Typicallyangles are 0°, 90° and/or 180°. A change in orientation of the device istypically accomplished manually. In another subvariant, each of theseats of a group is present on a separate turntable (211 a,b . . . )that is present on the rotary member (203) and can rotate independent ofthe spinning of the rotary member (203). The plane of rotation of aturntable is parallel to the spin plane of the rotary member. Theturntables (211 a,b . . . ) may be driven by an electric motor ormanually. A change of orientation may be accomplished automaticallyaccording to a predetermined time schedule defined by the processprotocol programmed into a controller of the instrument (not shown). Theuse of seats permitting separate rotation of microfluidic devices is inparticular of importance for variants in which α is 90° or essentiallyequal to 90°.

The ability of rotating a device 180° as described in the precedingparagraph permits reversal of the flow direction. It thus becomespossible to transport a liquid (including dissolved reagents anddispensed particles) back and forth in a part of a microchannelstructure.

One can also envisage that the possibility of reversing the liquid flowwill make it possible with extended microchannel structures comprisingextremely large number of functional units permitting more complexprocedures without increasing the size of a device. A microchannelstructure may thus start at one edge side, reach the opposite edge sidewhere a reversing unit permits the microchannel structure to go backtowards the starting edge side. Once the reagents/products etc that areunder processing end up in the reversing unit the device is rotated 180°and the process continued.

In other variants the seats can be moved laterally, for instance in aradial direction. In these variants it may be possible to regulate theflow velocity in the internal microconduit portions (308) by moving theseats (105,205) in the radial direction. Presuming constant spinvelocity, the flow velocity will increase when increasing the radialdistance by moving a seat outwards (and the microfluidic device), anddecrease when moving a seat inwards. By placing a number of essentiallyequal microfuidic devices at different radial distances a spectrum offlow velocities can be effectuated simultaneously.

The capability of radial movement of individual seats (105,205) willsimplify individual process treatments of the devices (101,201). Adevice may thus from time to time be separately placed at a more outwardposition than the other devices on the rotary member (103,203). Thiswill facilitate measurements, irradiations etc of part areas ofindividual microfluidic devices (101,201) that are presentsimultaneously on the rotary member (103,203).

The capability of radial movement also provide a simple way for thetransfer of microfluidic devices between two properly aligned innovativeinstruments, for instance in order to reverse the flow without rotatinga device 180°.

In still another subvariant, the seats may permit that microfluidicdevices (101,201) placed in the seats (105,205) can be moved upwardsand/or downwards in relation to the plane of the rotary member (103,203)(axial movement). The movement for a device/seat may be dependent orindependent from the movement of the other devices/seats. This variantwill also facilitate individual process treatments of the devices, e.g.measurement, irradiation etc.

The spinner motor (102,202) should be able to create the necessarycentrifugal force for driving a liquid between an upstream position anda downstream position in the internal microconduit portions (308) ofdevices that are placed on the rotary member (103,203). Centrifugalforce may be utilized in combination with a second liquid volume tocreate a sufficient local hydrostatic pressure within a structure todrive a first liquid volume through an outward (downward) and/or aninward (upward) bent of a microchannel structure. See for instance WO0146465. The spinner motor (102,202) should be able to provide spinvelocities that typically are within the interval 50-30000 rpm, such as50-25000 rpm, or part(s) of these intervals. Spinner motors providingeven higher spin velocities may be used. The spinner motor is preferablyregulatable in the sense that the spin velocity can be set to differentvalues and different accelerations and/or decelerations. Centrifugalforce may also be combined with other forces and/or means to driveliquid flow in a microfluidic device.

The Microfluidic Device

The microfluidic device (300) is illustrated in FIG. 3 as athree-layered variant comprising three planar substrates (I, II, andIII) where substrate I and substrate III have open microstructures intheir upper and lower surfaces, respectively, and substrate II has holespassing through the substrate. When the substrates are apposed assuggested in FIG. 3 d, the microchannel structures (304 a,b . . . ) areformed. The widths (a, b and c) of substrates I, II and III of thevariant of FIG. 3 are a=b>c. This means that the microfluidic device(300) typically comprises two essentially planar and parallel oppositesides (301 a and 302 in FIG. 3 d), and edge sides (303 a,b . . . in FIG.3 d). The parallel opposite sides typically defines a top side (301 a,b)and a bottom side (302) of the devices. The top side and/or the bottomside of the device are typically polygons, for instance with straightsides and perpendicular corners, such as in a rectangle, square etc(rectangular disc, square-shaped disc). Typically the top side and thebottom side have the same size and/or shape and are aligned in such away that edge sides are perpendicular to the top and bottom side. Thearea of an edge side is typically smaller than the area of the top sideand/or the bottom side.

The device (300) is preferably a disc or is disc-shaped. The disc may beplanar in which is included variants in which planar substrates ofdifferent lengths and/or widths have been used in the manufacture asillustrated in FIG. 3 d.

The number of microchannel structures (304 a,b . . . ) per device (300)depends on the size of the device and/or the individual microchannelstructures. Typically the microfluidic device comprises in total ≧2,such as ≧3 or ≧5 or ≧10 or ≧25 or ≧50 microchannel structures. A typicalupper limit is between 100 and 1000, such as between 100 and 500microchannel structures per device. The microchannel structures may bedivided into sets (sets I, II, III etc) depending on design, directionin the device, layer in which they extend in the device etc. The numberof microchannel structures in a set is typically within the interval of1-50, such as 2-25 or 2-20. Microchannel structures of the same set mayhave a common inlet port, possibly associated with a common distributionmanifold (see below). Many times there is only one set in each device.The microchannel structures of a set are typically essentially parallel.The layer (layer I) in which the microchannel structures of a set extendis typically parallel to the top side or to the bottom side of thedevice.

The prefix “micro” contemplates that each individual microchannelstructure (304) comprises one or more microcavities and/or microconduitsthat have a depth and/or a width that is ≦10³ μm, such as ≦5×10² μm or≦10² μm. Dimensions within this interval are preferably at hand in anylocation in a microchannel structure. The volume of a microcavity andthus also of liquid aliquots to be transported and processed aretypically in the nl-range, i.e. <5,000 nl, such as ≦1,000 nl, or ≦500 nlor ≦100 nl or ≦50 nl or smaller. There may also be larger microcavitiesextending above the nl-interval, e.g. with volumes 1-10 μl, 1-100 μl,and 1-1,000 μl (μl-range). These larger microcavities are typicallyassociated with inlet ports for liquid and used for the introduction ofsamples or washing liquids and the like.

Microcavities or microchambers may have the same or a differentcross-sectional geometry compared to surrounding microconduits.

The microchannel structures are typically enclosed, e.g. covered, buthave openings for inlet/outlet of liquid and/or air (ports/vents).

Different Parts of a Microchannel Structure

A microchannel structures (304) comprises the functional units that arenecessary to carry out a predetermined process within the structure andtherefore has at least:

-   -   a) one or more inlet arrangements each of which includes one or        more inlet ports (e.g. IP I₁ and IP I₂; 305 and 306 a,b . . . ,        respectively),    -   b) one or more outlet arrangement each of which includes one or        more outlet ports (OP I₁, OP I₂, OP I₃; 307 a,b . . . , 316, 320        a,b . . . ), and    -   c) an internal microconduit portion (308 a,b . . . ) between an        inlet arrangement and an outlet arrangement.

An inlet arrangement typically comprises also a volume-metering unit forliquids (309 a,b . . . and 310 a,b . . . ; FIGS. 3 c and 3 a,respectively) from which a metered liquid volume is transported furtherdownstream in the microchannel structure. As illustrated in FIG. 3 theremay be two kinds of inlet arrangements:

-   -   1) a common inlet port IP I₁ (305) together with a common        distribution system or distribution manifold (315) comprising        several volume-metering units (309), and    -   2) a separate port IP I₂ (306 a,b . . . ) and volume-metering        unit (310 a,b . . . ) for each microchannel structure.

An inlet arrangement may also comprise other functional units, e.g. aseparation unit for removing particulate material upstream avolume-metering unit. Separation units for removing particulate materialmay be based on sedimentation, filtering etc.

An outlet arrangement may or may not be directly linked to a downstreamend of an internal microconduit portion (308 a,b . . . ). FIG. 3illustrates three kinds of outlet arrangements:

-   -   1) an outlet port (OP I₁) (307 a,b . . . ) that is in        communication with the downstream end of the internal        microconduit portion (308 a,b . . . ) of a microchannel        structure and used for the disposal of processed liquid        aliquots,    -   2) an outlet port (OP I₂) (316) that is in communication with        the distribution manifold (315) and used for the disposal excess        liquid that has been dispensed to the distribution manifold        (315), and excess air,    -   3) an outlet port (OP I₃) (320 a,b . . . ) for the disposal of        excess liquid that has been dispensed to a single        volume-metering unit and is allowed to pass out via an overflow        microconduit (319 a,b . . . ) associated with the single        volume-metering unit (310 a,b . . . ).

An outlet arrangement may or may not comprise a waste treatmentfunction. Outlet ports are typicallya also used as air vents or outletsof air

The internal microconduit portion (308 a,b . . . ) typically comprisesone or more functional units in which a liquid, such as a sample, isprocessed. In this portion an active liquid flow is typically used fortransport of liquid, reactants and the like in at least a part of theportion.

An inlet port, such as IP I₁ (305) or IP I₂ (306), is primarily used asan inlet for liquid and/or particles (e.g. in suspensed form). An outletport, such as OP I₁ (307), is primarily used as an outlet vent for airand liquid. Ports may also have other functions or combinations offunctions, for instance selected from inlet for air (vent), outlet forair (vent), inlet for liquid, and outlet for liquid.

A functional unit (microconduit or system of microconduits) that iscommon to several microchannel structures is a part of each of themicrochannel structures it is common to. Inlet port 305 and also thedistribution manifold 315 in FIG. 3 are thus part of each microchannelstructure they are communicating with.

A volume-metering unit is used to meter a part of a liquid volume thathas been dispensed into the inlet port associated with the unit. Themetered volume is then further transported downstream into themicrochannel structure concerned from the inlet arrangement. Theprecision in the metering should be high, typically within the interval±10%, such as within ±5%, around a predetermined volume.

A volume-metering unit (309 a,b . . . , 310 a,b . . . ) typicallycomprises a volume-defining microcavity (311 a,b . . . (FIG. 3 c) and312 a,b . . . (FIG. 3 a), and a valve function (313 a,b . . . (FIG. 3 a)and 314 a,b . . . (FIG. 3 a)) that are associated with the lower end ofthe volume-defining microcavity (311 a,b . . . and 312 a,b . . . ,respectively). The valve functions (313 a,b . . . , 314 a,b . . . )prevent undesired leakage of liquid from the volume-metering units intodownstream parts of the microchannel structure(s). Typically there mayalso be an overflow microconduit (321,319 a,b . . . ) through whichexcess of air and/or of liquid is removed from the volume-meteringunits.

When two or more microchannel structures are associated with the sameinlet port (305) for liquid, the volume-metering units (309 a,b . . . )may define a distribution manifold (315) that is common for themicrochannel structures connected to the inlet port (IP I₁, 305). Thedistribution manifold (315) illustrated in FIG. 3 comprises a series ofvolume-metering units (309 a,b . . . ) and one or more outlet ports (OPI₂, 316) for excess air and excess liquid (overflow microconduit). Ifnecessary, inlet/outlet ports solely for air (inlet vents) (317 a,b . .. ) may be located at critical positions in order to support anefficient partition of well-defined liquid volumes to each of themicrochannel structures associated with the distribution unit. In thevariant shown in FIG. 3, critical positions are between thevolume-defining microcavities and/or on each terminal part (317 b-e and317 a,f, respectively). The positions of these inlet vents are selectedsuch that each inlet vent participates in defining the volume to bemetered in the microcavity concerned, for instance such that the volumebetween each pair of close vents will define the volume to be metered.Anti-wicking structures, for instance in the form of local changes inthe chemical or geometric surface characteristics may be present at thesame positions as the inlet vents (317 a,b . . . ) to assist in thevolume-definition. In order to prevent undesired passage of liquidthrough these inlet vents, the inside of the venting microconduits ofthe inlet vents (317 a,b . . . ) are typically hydrophobic (322 a,b . .. ), in particular at their connection to parts that are to containliquid.

When only one microchannel structure is associated with an inlet port(306), the volume-metering unit (310 a,b . . . ) typically comprises avolume-defining microcavity (312 a,b . . . ) which at its outlet end hasa valve function (314 a,b . . . ) and at its inlet end is connected tothe inlet port (306 a,b . . . ) via an inlet microconduit and to anoverflow microconduit (319 a,b . . . ) through which excess liquid canleave the main flow path. The cross-sectional area of thevolume-defining microcavity (312 a,b . . . ) is typically increasing atits inlet end where the over-flow microconduit (319 a,b . . . ) isattached and decreasing at its outlet end. The overflow microconduit(319 a,b . . . ) in the variant shown in FIG. 3 ends in an outlet port(OP I₃, 320 a,b . . . ).

Microconduits (overlow microconduits) (321 and 319 a,b . . . ) typicallyhave valve functions (331 and 332 a,b . . . , respectively).

In the preferred variants the volume-metering units are directeddownwards with their connections (valves 313 and 314) to downstreamportions of the microchannel structures (304 a,b . . . ) at the lowestlevel of each unit. The outlet ends (316 and 320 a,b) of the excessmicroconduits (321 and 319) are typically at a level that is lower thanthe inlet(s) vents (317 a,b . . . ), e.g. lower than the connectionbetween the corresponding volume-metering unit (309,310) and thecorresponding downstream parts of the microchannel structure, i.e.between a volume-metering unit (309,310) and an internal microconduitportion (308).

The level at which the inlet ports for liquid is located is not criticalas long as self-suction (capillarity) is relied upon for filling thevolume-metering units.

A volume-metering unit is capable of metering a liquid volume within theinterval/subinterval for volumes discussed elsewhere in thisspecification.

In order to prevent losses of metered liquids due to wicking,anti-wicking structures may be located between an inlet port for liquidand a volume-metering unit located downstream.

Further information on the design of distribution manifolds,volume-metering units, anti-wicking structures, valves, separation unitsfor removing particulate material etc can be found in for instance WO9853311 (Gamera Biosciences), WO 02074438 (Gyros AB), WO 0318198 (GyrosAB) and many others. See in particular units 3, 7, 10-12 (FIGS. 4, 8,11-13) in WO 0274438 and units B-D (FIGS. 3-5) in WO 0318198 (Gyros AB)and other passages related to anti-wicking structures and valves in thepublications cited in this specification.

Inlet ports that have the same function are typically present on thesame side, for instance on an edge side (303) or on the top side orbottom side (301,302). Inlet ports having different functions aretypically present on different sides, for instance on different edgesides (303 a,b,c or d), or on an edge side and on one of the parallelopposite sides (301,302), or on the top side and the bottom side(301,302). An inlet port, such as OP I₁ (305) in FIG. 3, that is commonfor several micochannel structures may thus be on one side, and an inletport, such as OP I₂ (306), that is only connected to a singlemicrochannel structure or to another combination of microchannelstructures on another one of the sides mentioned.

The opening of a port may be on a tip (323 and 324 in FIG. 3 c; 325 a,b. . . , 326 a,b . . . , and 333 in FIG. 3 a) that comprises amicroconduit that ends in the opening. The tip may be in the form of acapillary tube, triangular etc and may be an integral part of orseparately attached to the substrate(s) from which the microfluidicdevice is manufactured. A general term for this kind of port design is aprotrusion. Alternatively a port may be an opening directly in the flatsurface of the appropriate side of the device.

The protrusion design of the inlet ports is particularly well adapted toour innovative methodology herein called “Dip-Chip technique” whichcomprises that the loading of liquid is accomplished by simultaneouslydipping ports of the same kind into a liquid to be introduced. If thereare more than one inlet port of the same kind, the individual ports maybe dipped simultaneously into separate liquids, for instance into wellsof a microtitre plate. If the interior surface of the correspondinginlet arrangement(s) has/have a sufficient wettability as discussedelsewhere in this specification capillarity will cause the liquid tofill each of the microchannel structures (304) to the first valvefunction(s) (313 and 331 for inlet port 305, and 314 and 332 for inletports 306). Upon spinning the microfluidic device in the innovativeinstrument and opening the valve functions. (332 and 331) in theoverflow micrconduits (319 and 332, respectively), excess liquid willleave the microchannel structures via the overflow microconduits (321for inlet port 305, and 319 for inlet ports 306) leaving a well-definedvolume of liquid in each of the volume-defining microcavities (311 a,b .. . for inlet port 305, and 312 a,b . . . for inlet ports 306). Whenincreasing the spin velocity the liquid in the volume-definingmicrocavities will be transported further downstream to the reactionmicrocavities (327 a,b . . . ). If each of the reaction microcavitiesends with a valve function it will be possible to carry out a reactionat non-flow conditions. If the there is no valve function present thereaction is typically performed under flow conditions. Se further thepublications cited as background publications, in particular WO 0275312(Gyros AB) and WO 03093802 (SE 0201310-0) (Gyros AB).

Loading of ports that are plain openings in the flat surface of thedevice may be performed in 30 a conventional manner, typically by theuse of pipettes and/or more or less automated dispensers. If the sameliquid is to be introduced to all ports of a side, the side concernedmay simply be dipped into the liquid.

In certain variants there may be a need for inlet portions of differentmicrochannel structures to cross or intersect each other while keepingthem physically apart in order to avoid unwanted mixing of liquids. Thisis the case for variants in which

-   -   A) each microchannel structure of a set is linked to two or more        inlet ports for liquid and at least one of these ports is common        to several microchannel structures of the set, and    -   B) at least two of the inlet ports that are connected to the        same microchannel structure mouth in an edge side.

Placing crossing microconduit parts of different microchannel structuresin different sublayers can avoid the risk of undesired mixing. This isillustrated in FIG. 3 where the upstream part of inlet arrangement(s)that comprises/comprise one kind of inlet port (for instance inlet port305) is(are) in a sublayer that is physically separated from thesublayer comprising the upstream part of inlet arrangement(s) thatcomprise/comprises the other kind of inlet port(s) (for instance inletport(s) 306). The upstream part in this context comprises at least aninlet port with its inlet microconduit and possibly also thecorresponding volume-defining microcavity(ies) and/or any functionalunit, such as a separation function, that is located between the inletport and the volume-metering unit. The sublayer represented by theintermediate substrate II (FIGS. 3 b and d) typically provides forliquid communication between microconduits that are present in differentsublayers (e.g. substrates I and III) that are placed on different sidesof an intermediary sublayer/substrate (e.g. substrate II).

The internal microconduit portion (308) may comprise one or more of thefollowing functional units: microconduit for liquid transport, valveunit, branching unit, vent to ambient atmosphere (outlet port), unit formixing liquids, unit for performing chemical reactions or bioreactions,unit for separating soluble or particulate material from a liquid phase,waste liquid unit including waste cavities and overflow channels,detection unit, unit for collecting an aliquot processed in thestructure, possibly for further transfer to another device e.g. foranalysis, branching unit for merging or dividing a liquid flow, etc.Units may be combined, for instance detecting/measuring may take placein a reaction microcavity, for instance via a transparent wall(detection window) of this microcavity. The presence of functional unitsin the internal microconduit portion is illustrated in FIG. 3 where eachinternal microconduit portion (308) has a reaction microcavity (327 a,b. . . ). Depending on whether or not the reaction to be performed is totake place under non-flow conditions or flow conditions there may or maynot be a valve function (328 a,b . . . ) at the outlet end of themicrocavity (327). By making the wall of the reaction microcavitytranslucent/transparent (detection window, 329 a,b . . . ) it will bepossible to measure results of events taking place within the reactionmicrocavity.

Further details about useful functional units can be found in thepublications cited above, primarily with Gamera Biosciences/Tecan orGyros AB/Amersham Biosciences as assignees.

A microchannel structures typically has a main direction of liquid flow(D1) which is defined as the direction from the start to the end of theinternal microconduit portion (308 a,b . . . ) regardless of turns,branches, parts where the liquid is taken back and forth etc. In thecase there are no microchannel structures having other main directionsof flow, D1 for a microchannel structure will also be the main directionof flow for the device concerned. In a typical case D1 is directed fromone edge side (first edge side (303 a)) to another edge side of thedevice, e.g. an opposite edge side (second edge side (303 c)). Invariants of the microfluidic device (300) that allow for reversal ofliquid flow relative to D1, the main direction D1 is the main flowdirection in the initial part of the internal liquid microconduit (308),typically up to the stage where reversal occurs.

If not otherwise is apparent from the context, terms such as “higher”,“upper” and “inner” level/position of a microchannel structure (304) arerelative and means that the level/position concerned is located in adirection that is opposite to the main direction D1 compared to alevel/position that is at a “lower” level/position. The terms “up”,“upward”, “inwards” etc and “down”, “downwards”, “outwards” will mean“against” and “along”, respectively, the main direction D1 of amicrochannel structure.

The device (300) may be placed in a seat (105,205) on the rotary member(103,203). It is always possible to orient the disc plane outwards withthe upstream part of the internal microconduit portion (308 a,b . . . )at a shorter radial distance than the downstream part. This orientationmeans that the first edge side (303 a) becomes closest to the centre(axis of symmetry, spin axis) (104,204) of the rotary member (103,203).The main direction D1 of the device will be from the first edge side(303 a) (the centre) to the opposite edge side (303 c) (outwards),possibly at a certain angle (β) relative to the spin plane (−90°<β<90°with preference for −45°<β<45°, such as 0°).

Wettabillty/Non-Wettability of Inner Surfaces

The microchannel structures have in preferred variants inner surfacesthat are hydrophilic. Hydrophilicity may be introduced, for instance asdescribed in WO 0056808, WO 0147637, or U.S. Pat. No. 5,773,488 (GyrosAB). The hydrophilicity should be as given in these publications, i.e.the wettability of the interior of a structural unit should besufficient for capillary forces to fill the unit with liquid once theliquid front has passed the inlet of the unit. Where appropriatehydrophobic surface breaks (e.g. as anti-wicking means and/or valves)are introduced as outlined in WO 9958245 and WO 0274438. See also WO0185602 (Åmic AB & Gyros AB).

The exact demand on hydrophilicity (liquid contact angles) of innersurfaces of the microchannel structure may vary between differentfunctional units. Except for local hydrophobic surface breaks the liquidcontact angel for at least two or three inner walls of a microconduit ina particular unit should be wettable (=hydrophilic=liquid contactangle≦90°) for the liquid to be transported, with preference for liquidcontact angels that are ≦60°, such as ≦50° or ≦40° or ≦30° or ≦20°. Inthe case one or more walls have a higher liquid contact angle, forinstance is non-wettable (hydrophobic), this can be compensated by alowered liquid contact angle on the remaining walls. This may beparticularly important if non-wettable lids are used to cover openhydrophilic microchannel structures. The values above apply to thetemperature of use. The liquid referred to is typically water includingalso other aqueous liquids.

The liquid contact angles given above refer to equilibrium contactangles and measured at the temperature of use, for instance roomtemperature such as +25° C.±5° C.

What has been said above about hydrophilicity/hydrophobicity applies inparticular to the inlet arrangement of the microchannel structures (304)in the preferred microfluidic devices (300), including also the tip partof the microchannel structures, if present.

Microconduits that are used solely for venting purposes (inlet and/oroutlet venting) typically have hydrophobic inner surfaces at least attheir connection to a microconduit intended for liquid.

Valve Functions

Valve functions can typically be selected from three main categories:

-   -   1. Mechanical valves.    -   2. Valves that comprise intersecting channels together with        means that determine through which channel a liquid flow shall        be created.    -   3. Inner valves, i.e. valves in which the passage or non-passage        of a liquid depends on physical and/or chemical properties of        the liquid and the material in the surface of the inner wall at        the valve.

Type 1 valves typically require physically closing of a microconduit andare therefore called “closing valves”. They often have movablemechanical parts.

Type 2 valves function without closing and are therefore “non-closing”.A typical example is directing an electrokinetic flow at theintersection of two channels by switching the electrodes. See forinstance U.S. Pat. No. 5,716,825 (Hewlett Packard) and U.S. Pat. No.5,705,813 (Hewlett Packard).

In type 3 valves, the non-passage or passage of a liquid may be basedon:

-   -   (a) changing the cross-sectional area in a microconduit at the        position of the valve function by changing the energy input to        the material of the wall in the microconduit (closing valves),        and/or    -   (b) providing a boundary between surfaces of different        interaction energy with a through-flowing liquid at the valve        position (non-closing, capillary or passive valves), and/or    -   (c) a suitable curvature of the microconduit at the valve        function (geometric valves, non-closing).

Type 3a valves are illustrated in WO 0102737 (Gyros AB) in whichstimulus-responsive polymers (intelligent polymers) are suggested tocreate a valve function, and in WO 9721090 (Gamera Biosciences) in whichrelaxation of non-equilibrium polymeric structures and meltable waxplugs are suggested as valves.

Type 3b valves typically are based on local changes in chemical and/orgeometric surface characteristics. Through-flow is achieved byincreasing the force driving the liquid. The use of hydrophobic surfacebreaks (changes in chemical surface characteristics) as valves has beendescribed in WO 9958245, (Gyros AB) WO 0146465 (Gyros AB), WO 0185602(Åmic AB & Gyros AB), WO 0187486 (Gyros AB) and WO 0274438 (Gyros AB)and WO 031898 (Gyros AB). The use of changes in geometric surfacecharacteristics as valves has been described in WO 9615576 (DavidSarnoff Res. Inst.), EP 305210 (Biotrack), and WO 9807019 (GameraBiosciences). Other alternatives are a porous membrane having pores orclusters of small holes that require a sufficient driving force for theliquid to pass through. The pores/holes are typically hydrophobic andhave sizes corresponding to circular areas with a diameter ≦5 μm such as≦1 μm.

Type 3b valves often comprise an anti-wicking function if they utilizechanges in chemical and/or geometrical surface characteristics in edgesas described for anti-wicking structures.

Type 3c valves for centrifugal based systems may be achieved by linkingthe downstream end of a downwardly bent microconduit (U- or Y-shaped) toan upwardly bent microconduit. This is illustrated in WO 0146465 (GyrosAB) with two or more Y/U-shaped structures in sequence in the downstreamdirection.

If a closing valve is used in a microfluidic device, there is typicallyan outlet vent associated with the upstream end of the valve function.

Anti-Wicking Structures

Anti-wicking structures are typically local surface modifications thatcounteract wicking, i.e. undesired liquid transport in the inner edgesof microconduits. In microfluidic devices anti-wicking structures areparticularly important when retaining liquid volumes that are in thenl-range within predetermined microcavities.

An anti-wicking structure typically comprises a change in surfacecharacteristics in an inner length-going edge of a microconduit. Theedge typically starts in a microcavity and stretches into a microconduitconnected to the microcavity. The change may relate to a change ingeometric and/or chemical surface characteristics. Anti-wickingstructures may be present upstream or downstream a microcavity intendedto contain a liquid. An anti-wicking functionality may inherently alsobe present in inner valves that are based on the presence of ahydrophobic surface break in an inner edge.

A change in geometric surface characteristics is typically local and maybe selected from deformations, such as indentations and protrusions(projections). In most cases the deformation will also stretch into andacross an inner wall of the microconduit concerned. See further WO0274438 (Gyros AB) and WO 031898 (Gyros AB).

Deformations in the form of indentations, for instance in the form of“ear-like” or triangular, trapezoidal etc grooves as illustrated inFIGS. 3, 5, 8, 10, 11, 12 and 13 of WO 0274438, in FIGS. 2, 4 and 5 ofWO 031898 (Gyros AB), and in FIG. 1 of WO 0275312 (Gyros AB).

A change in chemical surface characteristics (surface break) foranti-wicking purposes means in a typical case that the inner surface ofa wettable microconduit comprises regions that are non-wettable. Theseregions are primarily present in inner edges of the microconduit butwill in the preferred cases extend fully between edges.

A change in geometric and a change in chemical surface characteristicsmay fully or partially coincide in the inner surface of microconduit.

Further information about various kinds of anti-wicking structurespossibly combined with an inner valve function is given in WO 0274438(Gyros AB) and in WO 031898 (Gyros AB).

Manufacture of the Microfluidic Device.

The microfluidic device may be manufactured from inorganic or organicmaterial. Typical inorganic materials are silicon, quartz, glass etc.Typical organic materials are plastics including elastomers, such asrubber silicone polymers (for instance poly dimethyl siloxane) etc. In apreferred variant, open microstructures are formed in the surface of aplanar substrate by various techniques such as etching, laser ablation,lithography, replication etc. From the manufacturing point of view,plastic material are preferred and the microstructures, typically in theform of open microchannels are formed by replication, such as embossing,moulding, casting etc. The microstructures are then covered by a topsubstrate that if required also is microstructured. See for instance WO9116966 (Pharmacia Biotech AB). The microstructures in the substratesare designed such that when the surfaces of two planar substrates areapposed the desired enclosed microchannel structure is formed betweenthe two substrates.

Microfluidic devices that require that different parts of a microchannelstructure are in different sublayers of layer I (=the layer in which themicrochannel structures of set I extend) may be formed by includingseveral substrate layers in the manufacturing method. See FIG. 3 and thetext above. A common inlet arrangement (305+309) as an uncoveredmicrostructure ay thus be defined in the surface of a first substrate(III, as indicated in the bottom side of the substrate) and the parts ofthe microchannel structures (304) that are not defined in the firstsubstrate (III) may be defined in the surface of one or more additionalplanar substrates (I, as indicated in the top side of the substrate).The microstructures in the substrates match each other such that whenthe substrates are apposed and joined together the microfluidic devicewith its microchannel structures will be formed. If needed there may bean intermediary planar substrate (II) placed between twojuxta-positioned substrates. An intermediary planar substrate (II) thatprovides for liquid communication (330 a,b . . . ) between parts of themicrochannel structures that are defined in different substrates (IIIand I). A hole, or a cluster of smaller holes or a porous membrane aretypically present at the locations where liquid communication is to takeplace. FIG. 3 also illustrates that a planar disc may be manufacturedfrom planar substrates having different forms (in this case breadths).In FIG. 3 the widths (a and b) of substrate III and II are equal andlarger than the width (c) of substrate I.

At the priority date of this invention the preferred plastic materialwas a) polycarbonates and plastic material comprising polyolefines.Polyolefins in this context are polymers comprising repeatinghydrocarbon monomeric units which preferably consist of one or morepolymerisable carbon-carbon doubles or triple bonds and saturatedbranched straight or cyclic alkyl and/or alkylene groups. Typicalexamples are Zeonex™ and Zeonor™ from Nippon Zeon, Japan, withpreference for the latter. See for instance WO 0056808 (Gyros AB).

The Second Main Aspect—The Instrument.

The instrument may be used in the innovative arrangement. The maincharacteristic feature is that the instrument comprises the kind ofseats (105 a,b . . . , 205 a,b . . . ) discussed for the first aspect ofthe invention. In other words the rotary member comprises seats, each ofwhich is capable of orienting layer I of a microfluidic device (300) inthe same manner as for the first aspect of the invention. Differentvariants are apparent from the description above and concern both theinstrument as such and features of the instrument that are related tothe microfluidic device to be used.

The Third Main Aspect—The Method/Use of the Instrument for ProcessingTwo or more Microfluidic Devices in Parallel.

This method/use comprises the steps of:

-   -   i) providing an instrument (100,200) of the second aspect of the        invention,    -   ii) providing one or more microfluidic devices (101,102,300)        that are adapted to be retained in the seats (105,205) of the        instrument (300),    -   iii) loading the necessary liquids, reactants, samples etc into        one or more of the microchannel structures (304) of each of the        microfluidic devices (300) provided in step (ii),    -   iv) placing the devices that has been loaded in step (iii) in        the seats (105,205) of the rotary member (103,203), and    -   v) processing the devices that have been placed in the        instrument in step (iv) by the use of at least one substep in        which a liquid flow is created in parallel in the microchannel        structures of the devices by spinning the rotary member        (103,203) around its spin axis (104,204).

Step iii) may be carried out before and/or after step iv). Reactants andother necessary chemicals may also be predispensed to the microchannelstructures (304), i.e. be included in the devices provided in step ii).If the microfluidic devices allow for it they may be loaded as outlinedby the innovative “Dip-Chip” technique. See the fifth aspect of theinvention. The innovative method may be part of a protocol comprisingseveral additional process steps within or external to the instrument.Such external process steps may take place prior to or after steps i)-v)or as a step inserted into this sequence of steps.

The Fourth Main Aspect—a Microfluidic Device.

This aspect is a variant of the microfluidic devices generally describedabove as a part of the innovative arrangement. The main characteristicfeature of the fourth aspect is a) that there is one, two or more inletports (305,306) in an edge side of the device (300), and b) that thehydrophilicity in the most upstream part of each of the microchannelstructure(s) (304 a,b . . . ) that is connected to this/these inletport/ports is/are such that at least a predetermined volume of liquid iscapable of penetrating this part in each microchannel structure byself-suction (capillarity). Each inlet port (305,306) may be in the formof a protrusion (324,333 a,b . . . ) comprising a microconduit asdescribed elsewhere herein. This volume may differ between the inletports of a set, for instance set I. It typically is at least the sum ofthe volume-defining cavities (311,312) in the volume-metering unit/units(309,310) which is/are associated with the inlet port concerned(305,306). See under the heading “Microfluidic devices” above.

In preferred variants the characteristic feature is that thecorresponding parts of the internal microconduit portion (308 a,b . . .) of each of the microchannel structures are at essentially the samedistance from said first edge side (303 a) or at the same level.

Further characteristic features of the innovative microfluidic devicehas been described above in the context of the first aspect of theinvention.

The Fifth Main Aspect—Loading by Dip-Chip Technique.

This aspect relates to a method for loading a microfluidic disc withliquid. The characteristic feature comprises the steps of:

-   -   (i) providing the microfluidic device of the fourth aspect of        the invention;    -   (ii) providing the liquids to be introduced through each kind of        inlet port(s),    -   (iii)dipping at least one kind of inlet port into the liquid        under sufficient time for the predetermined volume for this kind        of port to be sucked into the microchannel structures, and    -   (iv) defining a volume of the introduced liquid in each        volume-metering associated with the inlet port(s) used for the        introduction of the predetermined volume.

Step (iv) may be performed by utilizing centrifugal force for drivingthe liquid flow, for instance in an instrument of the present invention.Other driving forces may also be utilized by appropriately adapting themicrofluidic device to the instrument and driving force utilized.

In the case the kind of port utilizes comprises two or more ports anddifferent liquids are to be introduced through each of the ports, theseliquid are preferably provided in separate vessels, for instance inwells of a microtitre plate. In this case the distances between theports and/or between the wells are adapted to fit each other. Otherports may be used in the similar manner if they are adapted to theDip-Chip technique. Alternatively there may be ports that are adapted toconventional dispensation techniques, such as by drop dispensers,pipettes etc.

Subsequent to step (iv) the metered volumes are transported furtherdownstream in parallel in the microchannel structures associated withthe kind of inlet port(s) used.

Best Mode Embodiment

At the priority date the best mode embodiment corresponds to the variantshown in the drawings.

The invention is further defined in the appending claims that are partof the specification.

1. Microfluidic arrangement which comprises A) one or more microfluidicdevices, each of which comprises a set (set I) of one or moreessentially equal microchannel structures that are comprised within acommon generally planar layer of the device (layer I), each of saidmicrochannel structures comprises an internal microconduit portion inwhich an active liquid flow is used; and B) an instrument, which isintended for processing said one or more microfluidic devices andcomprises a spinner motor and a rotary member; characterized in that I)said rotary member comprises a group of one or more seats for holding atleast one of said one or more microfluidic devices, each of said seatsis capable of i) being positioned at the same radial distance as any ofthe other seats of the group, ii) aligning layer I essentially radiallyat an angle ax relative to the spin plane where 0°<α≦90°, withpreference for cc being essentially equal to 90°, and iii) preferablypositioning the corresponding positions in said microconduit portion ofsaid microchannel structures in any of said one or more microfluidicdevices at essentially the same radial distance, II) said internalmicroconduit portion has an upstream part that can be positioned at ashorter radial distance than a downstream part when the correspondingmicrofluidic device is placed in any of said one or more seats.
 2. Thearrangement of claim 1, characterized in that the seats are adjustablein the radial and/or the axial direction.
 3. The arrangement of claim 1,characterized in that the seats are at a fixed radial position.
 4. Thearrangement of any of claims 1-3, characterized in that each of saiddevices has two planar surfaces that are parallel to layer I andtypically are rectangular with preference for each of said devices beingdisc-shaped.
 5. The arrangement of claim 1, characterized in that theseats are capable of holding layer I of each of the microfluidic devicesat different angles relative to the radius passing through the seatconcerned, for instance at angles of 0°, 90° and/or 180°.
 6. Thearrangement of any of claims 1-5, characterized in that the microfluidicdevice is according to any of claims 7-19.
 7. A microfluidic devicecomprising i) two essentially planar and parallel opposite sides, andedge sides, ii) a set of one, two, three or more essentially equalmicrochannel structures, each of which comprises a first inletarrangement comprising an inlet port IP I₁, characterized in that a)each of the inlet ports is present in an edge side, and b) thewettability of the inner walls of said first inlet arrangement permitspenetration by self-suction (capillarity) of at least a predeterminedfirst volume of an aqueous liquid which is contacted with said one ormore inlet ports.
 8. The microfluidic device of claim 7, characterizedin that said first inlet arrangement is common for more than one of themicrochannel structures, such as all microchannel structures of the set.9. The microfluidic device of claim 7, characterized in that a) each ofsaid microchannel structures comprises a second inlet arrangementcomprising an additional inlet port IP I₂ which inlet arrangement andinlet port are connected to only one of the microchannel structures oris common for two or more microchannel structures, b) the wettability ofthe inner walls of the second inlet arrangement permits penetration byself-suction (capillarity) of at least a predetermined second volume ofan aqueous liquid which is contacted with IP I₂.
 10. The microfluidicdevice of claim 7, characterized in that either one or both of IP I₁ andIP I₂, if present, is/are part of a protrusion that is integral with orextends from the surface of the device.
 11. The microfluidic device ofclaim 7, characterized in that a) at least one of said first and/or saidsecond inlet arrangement, if present, comprises one volume-metering unitper microchannel structure associated with the arrangement, and b) saidvolume-metering unit has an outlet end associated with a valve function,preferably passive, which controls liquid transport through said outletend into downstream parts of the microchannel structure that isassociated with the volume-metering unit.
 12. The microfluidic device ofclaim 11, characterized in that a) the inlet port of either one or bothof said first and second inlet arrangements, if present, is fluidlyconnected to only one microchannel structure and b) the volume-meteringunit preferably has an overflow channel for defining the volume to bemetered in the unit.
 13. The microfluidic device of claim 11,characterized in that the inlet port of either one or both of said firstand second inlet arrangements if present, is fluidly connected to two ormore of the microchannel structures via a distribution manifoldcontaining one volume-metering unit per microchannel structure that isin fluid communication with the inlet port.
 14. The microfluidic deviceof claim 13, characterized in that said distribution manifold comprisesan excess microconduit that is common for all the volume-metering unitsof the manifold.
 15. The microfluidic device of claim 9, characterizedin that said wettability/hydrophilicity is present from IP I₁ or IP I₂,if present, to said valve function in each volume-metering unitconnected to the inlet port concerned, thereby permitting filling bycapillarity said inlet part to said valve function with said aqueousliquid.
 16. The microfluidic device of claim 11, characterized in thata) each of the volume-metering units is capable of metering a liquidvolume in the nanolitre range, e.g. ≦5000 nl such as ≦1000 nl or ≦500 nlor ≦100 nl, and b) each of said predetermined first and second (ifpresent) volume is essentially equal to the sum of the volumes ofliquids to be metered in the volume-metering units associated with theinlet arrangement/inlet port concerned.
 17. The microfluidic device ofclaim 7, characterized in that the inlet port(s) (IP I₁) of the firstinlet arrangement(s) is(are) present on one side, and the inlet port(s)(IP I₂) of the second inlet arrangemnt(s), if present, is(are) presenton a different side, preferably at least one of the IP I₁s and IP I₂s ispresent on an edge side or on different edge sides.
 18. The microfluidicdevice of claim 7, characterized in that it is manufactured from atleast two essentially planar substrates, one, two or more of whichdefine the individual microchannel structures.
 19. The microfluidicdevice of claim 7, characterized in that (i) each of said microchannelstructures extends in a layer of the device which layer is essentiallyparallel with said two opposite sides, (ii) each of said microchannelstructures comprises downstream one to said inlet arrangements aninternal microconduit portion in which active fluid flow can be used forthe transportation of liquid, reagents, analytes and the like, andpreferably corresponding parts of the microconduit portion of each ofsaid microchannel structures are at essentially the same distance fromsaid first edge side.